One known type of information storage device is a disk drive device that uses magnetic media to store data and a movable read/write head that is positioned over the media to selectively read from or write to the disk.
FIG. 1 illustrates a conventional disk drive device and shows a magnetic disk 101 as a medium for information/data storage mounted to and rotating round a spindle motor 102 at a high speed. A head gimbal assembly (HGA) 100 comprises a slider 104 containing read/write head for electric/magnetic signal transform and a suspension 110 mounting on the slider 104. The HGA 100 is attached to an arm 105 which rotates round a bearing 106. A voice-coil motor (VCM) 107 is provided for controlling the rotation of the bearing 106 and further controlling the movement of the arm 105 and, in turn, controlling the slider 104 to move from track to track across the surface of the disk 101, thereby enabling the read/write head to read data from or write data to the disk 101.
Now referring to FIG. 2, the suspension 110 includes a load beam 111, a base plate 112, a hinge 113 and a flexure 114, all of which are assembled together. In operation, the magnetic disk 101 creates an air bearing on which the slider 104 floats. The suspension 110 provides a spring force to counteract the force generated by the air bearing to position the slider at a “fly height”. Specifically, referring to FIGS. 3a-3b, the load beam 111 of the suspension 110 includes a dimple 115 thereon to transfer the spring forces generated by the load beam 111 to the flexure 114 at a position corresponding to a center of the slider 104. By this engagement of the dimple 115 with the flexure 114, the spring forces can be transferred to the slider 104 uniformly, thus making the slider 104 pitching and rolling at the fly height in response to fluctuations in the air bearing created by variations in the surface of the rotating disk 101. In this manner, the slider 104 is supported and can be positioned over the disk 101 by the HGA 100 in the disk drive to access or create information on the disk 101. In the operation process of the HGA 100 explained above, the dimple 115 of the suspension 110 plays an important role in achieving high precision read-write literacy of the slider 104, thus disk drive manufacturers are constantly seeking ways to form an excellent dimple 115 on the load beam 111.
FIGS. 4a-4b show a conventional dimple forming process. As shown in FIG. 4a, a base mould 210 is provided under the load beam 111 with a concave surface 211 of the base mould 210 aiming toward a first surface 116 of the load beam 111 at a position desired to form a dimple. A forming pin 220 is provided above the load beam 111 with a spherical surface 221 of the forming pin 220 aiming toward a second surface 117 of the load beam 111 opposite the first surface 116 at the position desired to form the dimple and punches the load beam 111 onto the base mould 210 in a first direction (shown as arrow V1), in which way a dimple 115 is formed on the load beam 111. Referring to FIG. 4b, the forming pin 220 moves away from the second surface 117 of the load beam 111 in a second direction (shown as arrow V2), and it is clearly shown that the dimple 115 formed by the forming pin 220 has a convex side on the first surface 116 of the load beam 111 and a concave side on the second surface 117 4 of the load beam 111.
However, in the process of forming a desired dimple on the load beam 111 mentioned above, because of no preparatory treatment performed on the load beam 111, the load beam 111 is deformed rapidly and violently in the forming pin punching step, which in turn, produces high stress at the junction of the dimple 115 and the load beam 111. This affects static attitude of the load beam 111 of the suspension 110, and further affects the assembly of the slider 104 with the suspension 110 of the HGA 100, and in turn, affect slider's read/write ability of the assembled HGA 100.
Hence, a need has arisen for providing improved dimple forming apparatus and method that do not suffer from the above-mentioned drawbacks.